Many implantable medical devices, such as neurostimulators, pacemakers and defibrillators, transmit electrical signals to provide therapy to a patient. Implantable medical leads deliver signals generated from such devices to tissue of the patient via one or more electrodes of the lead. Often the electrodes of the leads are located at a considerable distance from the implant location of the electrical signal generator device. If multiple leads are required or desired, separate subcutaneous paths may need to be tunneled for each lead, resulting in time consuming surgical procedures and potential patient discomfort.
In some situations a lead extension is employed to couple the lead to the signal generator. The lead extension may allow for connection of the lead in closer proximity to the tissue to which the generated electrical signal is applied, reducing the extent of tunneling required for the lead. However, the extension still needs to be tunneled through the patient.
When it is desired to implant two leads in the same general tissue location, a bifurcated lead extension with a single proximal leg may be employed. In such cases, one tunneling path may be made from the implant location of the electrical signal generation to a location close to the target tissue for the lead extension. The two leads may then be coupled to the extension at this location and may then traverse relatively short distances in the patient.
However, if more than two leads are desired, a single bifurcated extension is not sufficient and more than one extended subcutaneous tunneling procedure may be required. Further, bifurcated lead extensions tend to be of limited flexibility in terms of functionality. For example, if a proximal end of a bifurcated lead extension has eight discrete electrical contacts for making eight discrete electrical connections with an electrical signal generator, the bifurcated distal end will have two separate lead receptacles, each having four internal contacts for making electrical connections with four discrete contacts of a lead.